I would like to use a wipe to compare my grading with the original if this is possible or a stored frame if not. I'm missing something because if it works I'm not sure why and sometimes I get black instead of an image. Can anyone unconfused me, please?
If it's showing you black, then my guess is that it didn't play back the still correctly or just momentarily hiccoughed. I've seen this on occasion. Double-click a still in the Gallery again and hit "Toggle Wipe" when you right click in the Viewer and see if that does it. Command-W to turn Wipe on or off.